Repopulation of the irradiation damaged lung with bone marrow-derived cells.

Aim: The effect of lung irradiation on reduction of lung stem cells and repopulation with bone marrow-derived cells was measured. Materials and Methods: Expression of green fluorescent protein positive cells (GFP(+)) in the lungs of thoracic irradiated FVBINHsd mice (Harlan Sprague Dawley, Indianapolis, IN, USA) was determined. This was compared to the repopulation of bone marrow-derived cells found in the lungs from naphthalene treated male FVBINHsd mice and gangciclovir (GCV) treated FeVBN GFP(+) male marrow chimeric HSV-TK-CCSP. The level of mRNA for lung stem cell markers clam cell (CUT), epithelium 1 (FOXJ1) and surfactant protein C (SP-C), and sorted single cells positive for marrow origin epithelial cells (GFP(+)CD4.5(-)) was measured. Results: The expression of pulmonary stem cells as determined by PCR was reduced most by GCV, then naphthalene, and least by thoracic irradiation. Irradiation, like GCV, reduced mRNA expression of CCSP, CYP2F2, and FOXJ1, while naphthalene reduced that of CCSP and CYP2F2. Ultrastructural analysis showed GFP(+) pulmonary cells of bone marrow origin. with the highest frequency being found in GCV-treated groups. Conclusion: Bone marrow progenitor cells may not participate in the repopulation of the lung following irradiation.